Studies of structural disorder of self-assembled thiol monolayers on gold by cyclic voltammetry and ac impedance

Diao, Peng; Jiang, Dianlu; Cui, Xiaoli; Gu, Da-Ming; Tong, Ruting; Zhong, Bing

doi:10.1016/s0022-0728(98)00470-7

Cited by 135 publications

(113 citation statements)

References 36 publications

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“…Moreover, a significant inhibition of the Ru(NH 3 ) 6 3+ reduction is also shown. 6 3−/4− on a gold electrode coated by thiols [34]. This behavior is consistent with the kinetic model of thiol adsorption proposed by Nuzzo and coworkers [35].…”

Section: Sam Of C 16 Sh On Ag(iii)supporting

confidence: 88%

On the Contrasting Effect Exerted by a Thin Layer of CdS against the Passivation of Silver Electrodes Coated with Thiols

et al. 2018

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Abstract:The passivation of metal electrodes covered by self-assembled monolayers of long-chain thiols is well known. The disappearance of the voltammetric peak of redox species in solution is a classical test for the formation of full layers of thiols. Similar studies on semiconductors are still very limited. We used silver surfaces covered by an ultrathin layer of CdS as substrate for self-assembling of n-hexadecanethiol (C 16 SH), and we compared the experimental results with those obtained by using the bare silver surface as substrate. The strong insulating effect of C 16 SH deposited on Ag(III) is shown by the inhibition of the voltammetric peak of Ru(NH 3 ) 6 3+/2+ . On the contrary, the voltammogram obtained on CdS-covered Ag(III) is very similar to that obtained on the bare Ag(III) electrode, thus suggesting that the presence of CdS exerts a contrasting effect on the passivation of the silver electrode. A crucial point of our work is to demonstrate the effective formation of C 16 SH monolayers on Ag(III) covered by CdS. The formation of full layers of C 16 SH was strongly suggested by the inhibition of the stripping peak of Cd from the CdS deposit covered by C 16 SH. The presence of C 16 SH was confirmed by electrochemical quartz crystal microbalance (EQCM) measurements as well as by Auger electron spectroscopy (AES) analysis.

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Section: Sam Of C 16 Sh On Ag(iii)supporting

confidence: 88%

On the Contrasting Effect Exerted by a Thin Layer of CdS against the Passivation of Silver Electrodes Coated with Thiols

et al. 2018

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“…Assim, somente uma pequena porcentagem das biomoléculas na superfície do eletrodo permanece ativa e mantém sua capacidade de interagir seletivamente com as moléculas do analito 103 . A auto-organização molecular tem se tornado um procedimento de derivação de superfícies bastante popular 12,13,[20][21][22]81,[104][105][106][107] , principalmente devido à sua simplicidade, versatilidade e possibilidade de produzir, em escala molecular, estruturas altamente ordenadas. Este tipo de modificação tem apresentado uma excelente estabilidade frente a uma ampla faixa de potenciais de trabalho, e também fornece um microambiente favorável para a atividade biocatalítica das enzimas, pois pode simular membranas biológicas, aproximando o sistema das condições conformacionais ótimas observadas nos ambientes biológicos originais 105 .…”

Section: Eletrodos Modificados Com Sam -Análise De Compostos Orgânicosunclassified

Emprego de monocamadas auto-organizadas no desenvolvimento de sensores eletroquímicos

Freire¹,

Pessôa²,

Kubota³

2003

Quím. Nova

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Recebido em 18/7/02; aceito 9/10/02 SELF-ASSEMBLED MONOLAYERS APPLICATIONS FOR THE DEVELOPMENT OF ELECTROCHEMICAL SENSORS. Selfassembled monolayers (SAMs) modified electrodes exhibit unique behavior that can greatly benefit electrochemical sensing. This brief review highlights the applications of SAM modified electrodes in electroanalytical chemistry. After a general introduction, which includes the approaches for SAM development, different electrochemical systems for detecting inorganic and organic species are described and discussed. Special attention to the coupling of biological sensing element to the SAM is given, which can selectively recognize the analyte. Future prospects are also evaluated.Keywords: chemically modified electrodes; self-assembled monolayers; electrochemical sensors. INTRODUÇÃOO desenvolvimento de sensores eletroquímicos é uma das áreas de maior e mais rápido crescimento dentro da Química Analítica, principalmente devido aos novos desafios impostos por amostras de interesse industrial, clínico e ambiental, que têm levado a uma crescente busca por sensores com melhores características, tais como alta sensibilidade, seletividade e estabilidade [1][2][3][4][5][6][7][8] . Apesar da grande versatilidade e perspectivas apresentadas pelos sensores eletroquímicos, a utilidade de um eletrodo é muitas vezes limitada devido a uma passivação gradual de sua superfície, que é conseqüência principalmente da adsorção dos produtos da própria reação de óxido-redução utilizada na detecção, ou ainda, dos sub-produtos destas reações que podem se polimerizar e se depositar sobre a superfície dos eletrodos 6 . Além disso, a sensibilidade de muitos analitos importantes pode ser prejudicada em função da cinética de transferência de elétrons entre estes compostos e os materiais dos eletrodos ser excessivamente lenta 9 . Uma outra limitação é a dificuldade de discriminar entre compostos alvos que possuam características redox similares 9 . Uma área que oferece grande potencial para minimizar os problemas acima descritos, e conseqüentemente para aumentar a aplicabilidade e eficiência dos sensores eletroquímicos, é a que compreende os chamados eletrodos quimicamente modificados (EQM) 9,10 . A habilidade para controlar e manipular deliberadamente as propriedades das superfícies dos eletrodos pode proporcionar uma variedade de efeitos atrativos, levando a superfícies com características que podem contornar efetivamente muitos dos problemas apresentados pelos sensores eletroquímicos tradicionais.Estudos experimentais, suportados pela teoria, têm mostrado que a velocidade de transferência de elétrons pode ser sensivelmente afetada em função da modificação da superfície dos eletrodos 11. A classificação das reações do eletrodo pode ser feita com base no grau de interação entre os reagentes e a superfície do eletrodo, ocorrida durante o estado de transição da transferência de elétrons 12 . Os processos de transferência de elétrons onde as interações entre as espécies reagentes e a superfície do eletrodo são fracas e não es...

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“…Third, it is worth noting here that the long chain MEODA did not effectively block electron-transfer as one usually sees with long-chain alkylthiol SAMs. 34,35 It is well known that long-chain alkanethiol SAMs easily (even in few minutes) form highly integrated, well packed and pinhole-free SAMs on gold. This weak blockage of the electrode surface by the long-chain MEODA, even after long-hour deposition, is attributed to the spaces/pores created by the presence of the amide bond in its molecular structure, similar to that seen recently by Wilkop et al 36 in their work with the disulfide-terminated hexyl thioctate SAM that contained oxo-containing moieties.…”

Section: Cyclic Voltammetry Characterisationmentioning

confidence: 99%

Electron transfer dynamics across self-assembled N-(2-mercaptoethyl) octadecanamide/mycolic acid layers: impedimetric insights into the structural integrity and interaction with anti-mycolic acid antibodies

Ozoemena

Mathebula

Pillay

et al. 2010

Phys. Chem. Chem. Phys.

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The integrity and properties of mycolic acid (MA) antigens integrated into a self-assembled monolayer (SAM) of N-(2-mercaptoethyl)octadecanamide, (MEODA), on a gold electrode have been interrogated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). EIS data showed that Au-MEODA and Au-MEODA-MA behave as microelectrode arrays, with pinholes acting as the microelectrodes that permit electron transport between a redox-active probe in solution and the underlying gold surface. The average radii of the pinholes (r a ) and half the distance between the centers of the neighbouring pinholes (r b ), were estimated from EIS using the pore size model, and discussed. Anti-MA antibodies present in a tuberculosis (TB)-infected patient (co-infected with HIV) strongly interact with Au-MEODA-MA showing a rather compact and stable bio-complex structure that is virtually defect-free. The electrochemical impedimetric properties associated with the ability of the Au-MEODA-MA to discriminate between TB positive and negative human sera are also discussed. We prove that the Au-MEODA and Au-MEODA-MA electrodes, as well as the MA-anti-MA antibody interactions, are characterized with time-constant dispersion, typical of microstructures with grain/grain boundary phases. These crucial physico-electrochemical insights into the behaviour of surface-confined MA should provide a useful basis for the design and development of a potential impedimetric immunosensing platform for active tuberculosis.

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Studies of structural disorder of self-assembled thiol monolayers on gold by cyclic voltammetry and ac impedance

Cited by 135 publications

References 36 publications

On the Contrasting Effect Exerted by a Thin Layer of CdS against the Passivation of Silver Electrodes Coated with Thiols

On the Contrasting Effect Exerted by a Thin Layer of CdS against the Passivation of Silver Electrodes Coated with Thiols

Emprego de monocamadas auto-organizadas no desenvolvimento de sensores eletroquímicos

Electron transfer dynamics across self-assembled N-(2-mercaptoethyl) octadecanamide/mycolic acid layers: impedimetric insights into the structural integrity and interaction with anti-mycolic acid antibodies

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